The State Department says the United States and Libya have formally re-established diplomatic relations after a 24-year break. The announcement came at the end of a two-day visit to Tripoli by a senior-level U.S. delegation headed by Assistant Secretary of State William Burns.

The two countries have had diplomatic representatives in each other's capitals since last February as so-called "interest sections" operating out of other countries' embassies.

But the U.S. statement, issued in Tripoli and Washington late Monday, puts a formal stamp on the process of rapprochement that began last December with Libya's announcement that it was renouncing weapons of mass destruction.

It said Mr. Burns "formally inaugurated the new U.S. liaison office in Tripoli and resumption of direct diplomatic ties," and said Libya will be taking its own steps to establish diplomatic representation in the United States.

It said the Burns delegation reiterated President Bush's commitment "to reciprocate in good faith" as Libya implements its disarmament commitments, and that the establishment of the diplomatic missions will assist this "step-by-step process" of strengthening relations.

Mr. Burns was accompanied to Libya by the State Department's ambassador-at-large for counter-terrorism, Cofer Black. And officials here said they raised with the Libyans reports that Mr. Gadhafi last year authorized a plot against Saudi Arabia's de facto ruler, Crown Prince Abdullah.

Libya denied involvement when news reports surfaced earlier this month, and also assured U.S. officials it would not use violence to settle disputes with other countries.

At a Washington news briefing, State Department deputy spokesman Adam Ereli said the U.S. team "reminded" Libyan officials of that commitment.

He said U.S. investigations of the matter continue, and given that reports of the plot are unverified, they have had no impact thus far on the bilateral relationship.

"We are looking into these reports. We are trying to establish their veracity or not," he said. "That veracity has not yet been fully established. I will not speculate on what may or may not happen if they were, because that is speculation. We can deal with the here and now. The here and now is that we've got a process under way with Libya, that process is moving forward satisfactorily, and that we will act accordingly."

In an interview with Arab newspapers published Saturday, Secretary of State Colin Powell said the alleged plot is a "serious allegation" that the Bush administration is taking into account as it lays out a "road map" for Libya to return to a more normal relationship with Washington.

The Bush administration has already lifted some economic sanctions against Libya, but others remain because of that country's continued presence on the State Department's list of state sponsors of terrorism.

The statement on the Burns visit said the U.S. side welcomed a Libyan assurance that it stood by its commitments to fulfill U.N. resolutions on the bombing Pan Am flight 103, a 1988 terror attack for which Libya has admitted responsibility and agreed to pay compensation.

It also said the United States expressed appreciation for Libya's efforts to address the "tragic" humanitarian situation in the western Darfur region of Sudan, and that they will continue cooperation on the issue.

White House National Security Adviser Condoleezza Rice said Sunday the United States is working with Libya to try to establish a new route for relief supplies to get into Darfur, which adjoins Libyan territory, and where hundreds of thousands of people displaced by civil conflict are in dire need of assistance.